In a conventional liquid transfusing set (liquid transfusing apparatus), a liquid transfusing tube is provided with a male lure connector at its end part (distal end) on the side of connection to a patient. Therefore, in order to secure a plurality of liquid transfusing routes, it has been necessary to provide the tube on the patient's side with a three-way cock, a multiple-way cock, or the like so as to obtain the condition in which a liquid transfusing route or routes can be additionally provided, i.e., the plurality of liquid transfusing tubes can be connected (see, for example, Japanese Patent Laid-open No. Hei 4-354952).
For example, although liquid transfusing sets having a three-way cock provided at an intermediate part of a liquid transfusing route have been commercialized, the number of liquid transfusing routes required varies depending on the patient or the patient's condition, and the number of liquid transfusing routes, which must preliminarily be prepared, is not known. In view of this, it is a general practice to collect data on the number of liquid transfusing routes used from many patients, calculate an average number of liquid transfusing routes used from the data, and configure the liquid transfusing routes by providing reserve ports capable of connection with liquid transfusing tubes the number, which number is one or two greater than the average number of liquid transfusing tubes used.
However, the patients requiring the reserve ports are in many cases those whose conditions are highly liable to change suddenly, and most of the patients to be treated by the liquid transfusing treatment do not require the reserve ports. However, the liquid transfusing sets provided with the reserve ports must be prepared for the small number of patients, which raises the cost of the liquid transfusing sets, or increases the number of kinds of the liquid transfusing sets to be prepared in each hospital, which costs much for stock control, leading to a rise in medical expense.
In addition, when the number of kinds of liquid transfusing sets has been increased, it is necessary to selectively use the different kinds of liquid transfusing sets, leading to a higher risk of making a mistake in the method of using the same.
Moreover, when the patient's condition has changed suddenly or in other similar situations, the reserve ports prepared beforehand may temporarily become insufficient.
In such a case, it is necessary to once stop the liquid transfusion, occlude the liquid transfusing route, then open the liquid transfusing route, and to assemble a three-way cock or the like into the course of the liquid transfusing route. In this instance, it is necessary to carry out a work needing much labor and time, i.e., to assemble the cock into the liquid transfusing route, apply syringe suction for removing air, which has been mixed into the liquid transfusing route on the patient's side, perform priming of the liquid on the stopped side, thereby eliminating air stagnating in the liquid transfusing route, and then to connect the liquid transfusing tube.
Besides, the liquid transfusing routes may be mis-connected, or dosing speed may be mis-set in again setting the flow rate (setting the dosing speed).
In addition, when suction through a syringe is applied to removal of air present in the liquid transfusing route on the patient's side, the patient's blood may flow back into a catheter indwelling in the patient, and the blood may become liable to coagulate, possibly causing the formation of thrombus. Therefore, it becomes necessary to exchange the indwelling catheter earlier than scheduled, which adversely affects the patient.
Besides, although there are needleless connectors developed for preventing puncture accidents in medical staff or for maintaining cleanliness at the time of connection, the needleless connectors are based on the assumption of closed circuits. Therefore, it is impossible to increase the number of liquid transfusing tube connection locations in the course of the liquid transfusing route. In the situation where the number of the connection locations is insufficient, it is necessary to adopt a use method in which the portion on the distal end of the liquid transfusing route provided with the needleless connector is opened and which considerably impairs the characteristic feature of connecting the liquid fusing tubes while maintaining the cleanliness in a closed circuit. Also in this case, like in the above-mentioned case, the method in which a larger number of reserve ports than expected to be needed are provided results in that it is unknown how many reserve ports should be provided. Eventually, the number of reserve ports will be insufficient. In this manner, the rise in cost, the labor and time taken for air removal, the risk of generating a mistake in setting the dosing speed, and a cause of thrombus, are the same as in the above-mentioned case.